JP2002184424A - Column type electrochemical cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve electrolysis reaction and charging and discharging reaction efficiency of a redox flow type cell. SOLUTION: Internal carbon fibers 51 which become a first electrode are filled into the inside of a porous tubular diaphragm 50 composed of a cylindrical diaphragm body in the direction of circulation of a first electrolyte. The multiporous tubular diaphragm 50 is inserted into a through hole 53 which is drilled in a central part of an electrochemical cell body 52 and becomes a first flow passage and then is fixed. A plurality of through holes 55 for filling external carbon fibers 54 which become a second electrode which become second flow passages are drilled in a peripheral part of the through hole 53. A total of cross sectional areas of the through holes 55 is set to be substantially equal to an internal cross sectional area of the multiporous tubular diaphragm 50 substantially. The electrochemical cell body 52 is formed by a rectangular member in which a plurality of through holes 55 are drilled in predetermined positions. After that, the through hole 53 in which the multiporous tubular diaphragm 50 is inserted is drilled in a predetermined position in the central part of the electrochemical cell body 52.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reaction cell for chemically reacting a substance in a solution by an electrochemical oxidation / reduction electrolysis method, and more particularly to a redox flow type battery for reacting while moving a liquid. TECHNICAL FIELD The present invention relates to an improved column-type electrochemical cell which ensures electrical connection to a working electrode of a flow-type column-type electrochemical cell such as a cell or a water electrolysis refining device, and enhances reaction efficiency.

[0002]

2. Description of the Related Art Recently, a chemical substance present in a liquid is electrochemically oxidized and reduced to synthesize another new substance, or electrolytically produced water containing a large amount of acidic ions and alkali ions. Or, recently, a new field by electrochemical reaction technology is being pioneered, such as application to a redox battery cell as a secondary battery for power storage corresponding to leveling of power load.

[0003] This electrochemical reaction means that a working electrode and a counter electrode are placed in a liquid so as to face each other, a predetermined DC voltage is applied between the electrodes, and electrons are exchanged with a reactant in the liquid that is in contact with both electrodes. Oxidation or reduction. Therefore, it is desirable that the reactants in the liquid react as much as possible by one energization, and increasing the reaction efficiency is an important factor required for an electrochemical cell. In addition, since various substances mixed in the liquid have different degrees of reaction depending on the potential applied between the electrodes, it is important that the potential on the surface of the reaction electrode is uniformly distributed.

As an electrochemical reaction cell most suitable for such requirements, there is a column-type electrolytic cell developed by Fujinaga, Kihara and others. In particular, as a commentary by Kihara, the technical journal "Analytical Chemistry" published by the Japan Society for Analytical Chemistry (1973
Vol.22, No12) “Electroanalytical Chemistry Using Column Electrodes”
Is described in detail.

Utilizing the above technical features, there is Japanese Patent Application No. 10-284659 proposed as a "flow type column electrosynthesis cell" by Sueoka et al. As a practical reaction cell. Next, this proposal will be described with reference to FIG.

In FIG. 5, reference numeral 1 denotes a box-shaped cell main body, and 2 denotes a porous glass tube (column) as a porous diaphragm tube arranged to penetrate the cell main body 1 in the horizontal direction. In this porous glass tube 2, carbon fibers 3 formed in a thread shape as a working electrode are densely filled in the axial direction of the tube, and both ends of the porous glass tube 2 are provided to prevent liquid leakage. Are fixed to the flange 6 and the holding plate 7 via the O-rings 4 and 5. 8, 8 are screws for fixing the flange 6, 9, 9 are screws for fixing the holding plate 7, and 1a is a lid member. The carbon fiber 3 may be in the form of a thread, a fiber, a particle,
It may be processed into a mesh shape or a ribbon shape.

The holding plate 7 is provided with one end of an electrode rod 10 made of glassy carbon or the like protruding. The holding plate 7 is fixed by a side plate 11 using a screw 12 and an O-ring 13 for preventing liquid leakage. The side plate 11 is formed with a hole 11 a where the protruding end of the electrode rod 10 is desired. The other end of the electrode rod 10 is inserted and connected to a substantially intermediate position of the carbon fiber 3 serving as a working electrode in the cell body 1. As described above, the side plate 11 has a function as a support member for the electrode rod 10.

Here, the energizing mechanism of the electrode rod 10 will be described. A cap-shaped energizing member 14 is connected to the electrode rod 1 through a hole 11a opened in a side plate 11 as an electrode rod supporting member.
Insert and contact in the direction of 0 axis.

Next, the coil spring-like elastic member 15
The external conductor 16 integrally formed with the elastic member 15 is fitted into the hole 11 a of the electrode rod 10 in the axial direction.
Is pressed against the cap-shaped conducting member 14. Thereafter, an elastic member holding screw 17 as a fixing member is screwed into the hole 11 a from outside the side plate 11, and the energizing member 14 is electrically connected to the end of the electrode rod 10 by the coil spring-like elastic member 15. Press to obtain With such a configuration, the electrical contact between the electrode rod 10 and the external conductor 16 is strengthened.

Further, as described above, the electrode rod 10 is connected to one end of the carbon fiber 3 as a working electrode.
Thus, the insertion position of the electrode rod 10 with respect to the carbon fiber can be accurately adjusted by changing the screwing position of the elastic member pressing screw 17.

Further, a pipe 19 for introducing an electrolytic test liquid is inserted through a connector 18 from the side of the holding plate 7.
An inner distal end 19a of the pipe 19 is connected to a cylindrical liquid passage 7a provided inside the holding plate 7, and the electrolytic test solution is supplied from the distal end 19a of the pipe 19 through the liquid passage 7a to the cell body. 1. A pipe 20 a for discharging a test solution is inserted through the other flange 6 via a connector 20.

As the porous glass tube 2, for example, a Vycor glass tube is used. Instead of the thread-like carbon fiber 3, a working electrode processed into a fiber shape, a particle shape, a mesh shape or a ribbon shape is used as a working electrode. Is also good. The porous glass tube 2 used as the diaphragm tube is not limited to this, and may be replaced with a ceramic, enamel, or cast tube having fine through holes.

The porous glass tube 2 has numerous fine holes, for example, holes having a diameter of about 50 °, penetrating innumerably from the surface toward the inside of the tube, and does not allow the passage of substances such as water but the passage of ionic substances. Therefore, it can be used as a high quality diaphragm. A platinum wire 21 is wound around the outer periphery of the porous glass tube 2 a required number of times as a counter electrode. Platinum wire 2
One end of 1 is led out through a connector 22a fixed to the lid member 1a as a counter electrode terminal 22.

A liquid reservoir 25 is formed in the box-shaped cell main body 1. In the liquid reservoir 25, a predetermined amount of an electrolytic solution 26 containing a required amount of a conductive material, for example, salt, is added. The porous glass tube 2 and the platinum wire 21 are arranged so as to be immersed in the electrolytic solution 26. Further, the reference electrode 27 is inserted through the lid member 1a and inserted into the electrolytic solution 26 via the connector 27a.

In the cell configured as described above, an electric current flows between the carbon fiber 3 and the platinum wire 21 to electrolyze the electrolytic solution 26 flowing along the surface of the carbon fiber 3. Then, the electrolytic surface area is very large, the thickness of the flowing liquid layer is small, and furthermore, there is almost no difference in the potential distribution between the inlet and the outlet of the flow of the carbon fiber 3 (the carbon fiber is electrically By virtue of being a good conductor, a highly efficient electrolytic cell can be obtained in which the target electrolytic substance is almost electrolyzed in one pass.

Also, the pinhole of the porous glass tube 2 is small, and the electric resistance of the tube 2 is also small.
Due to the former feature, there is almost no fear that the electrolytic solution inside and outside the glass tube is mixed, and from the latter feature, electrolysis can be performed by precise potential control. Due to these features, the column (cylindrical) electrochemical cell described above is applied as various types of electrolytic reaction devices.

In addition to the above-mentioned devices, recently new applications include, for example, generation of electrolyzed water having an acidic or alkaline property, or application of sterilizing harmful microorganisms (bacteria) or the like existing in service water by electrolysis or power generation equipment. Application to a redox flow battery applied to a power storage system for load leveling is being studied.

In the electrochemical cell shown in FIG.
Although the electrolytic efficiency of the electrolytic solution 26 in the inside does not matter, and therefore the electrolytic surface area is small, as a new application as described above, the electrolytic solution 26 in the liquid reservoir 25 is allowed to flow, and the electrolytic solution 26 is also used in the glass tube 2. It is important that the electrolyte is electrolyzed to the same extent as the electrolyte.

In the redox flow type battery, it is necessary to simultaneously perform oxidation and reduction reactions on the surfaces of both electrodes through a diaphragm in the course of charging and discharging, respectively, with an electrolyte containing substantially the same amount of a battery active material. .

FIG. 6 is a schematic structural view of a redox flow battery. In FIG. 6, reference numeral 81 denotes a cell body, and the cell body 81 is divided into two rooms by a diaphragm 82 made of an ion exchange membrane. Both rooms have a positive electrode electrolyte tank 83
And pump 8 from anode electrolyte tank 84 separately.
The electrolyte is supplied by 5, 86. In both rooms, electrodes 87 and 88 made of carbon felt are provided, and an AC / DC converter 89 is connected to both electrodes.

A substation equipment 90 is connected to the AC / DC converter 89, and the converter 89 is used to store electric power.
Is stored in the battery. When discharging the stored DC power, the converter 89 is inversely converted and supplied to the customer.

[0022]

For the reasons described above, a redox flow battery has a structure in which both electrolytes are passed. In addition to this redox flow battery, FIG.
The use of a flat type electrolytic cell having the structure shown in FIG.

In FIG. 7, first and second containers 32 and 33 are formed with a plate-shaped diaphragm 31 interposed therebetween.
2 and 33 are filled with first and second carbon fibers 34 and 35. The first and second containers 32 and 33 have first and second liquid inlets 36 and 37 and first and second outlets 3 respectively.
8, 39 are provided. For the purpose of electrical connection, for example, first and second platinum wires 40 and 41 are inserted into the first and second carbon fibers 34 and 35, respectively. The first and second platinum wires 40 and 41 are connected to the first and second containers 32,
The first and second terminals 42 and 43 provided outside the unit 33 are connected via first and second lead wires 44 and 45. As the plate-like diaphragm 31, an ion exchange membrane is usually used.

Next, the generation of electrolyzed water using the electrolysis cell configured as described above will be described. For example, an appropriate amount of saline (NaCl) is dissolved in pure water, and the saline is introduced into the liquid inlet. 4
6 and the first and second terminals 42, 43
For example, when a DC voltage of 1.0 V with the first terminal 42 side being positive is applied between the first terminal 42 and the second terminal 42 through the plate-like diaphragm 31.
Electric current flows between the carbon fibers 34 and 35.

Then, strongly acidic electrolyzed water is generated on the first liquid outlet 38 side and alkaline water is generated on the second liquid outlet 39 side, and this electrolyzed water is used for sterilization of microorganisms and the like. . It is difficult to make the electric potential distribution of the first carbon fiber 34 and the second carbon fiber 35 uniform in the flat plate type electrolytic cell, and this does not cause much problem as an application for applying a relatively high electric potential such as electrolyzed water. And electrolysis at a relatively low potential of 0.5 V or less, there is a problem that the electrolysis reaction efficiency is lowered.

The present invention has been made in view of the above circumstances, and ensures the electrical connection to the working electrode of a flow column type electrochemical cell in which a reaction is performed while moving a liquid, and improves the reaction efficiency. An object of the present invention is to provide a column-type electrochemical cell.

[0027]

In order to achieve the above-mentioned object, a first aspect of the present invention is directed to an electrochemical cell main body in which a first and a second electrolyte are respectively formed with an inlet and an outlet. And first and second flow paths formed in the cell body and guiding first and second electrolytes introduced from the respective introduction holes to the respective discharge holes, and the first and second flow paths The diaphragm body formed of a porous member disposed in the first flow path so as to form the two flow paths so as not to mix the two electrolyte solutions flowing through the first flow path and to cause an electrochemical reaction between the two electrolyte solutions. Is inserted into the first and second flow paths partitioned by the diaphragm, and a voltage is applied so that the potential distribution becomes uniform in order to cause an electrochemical reaction between the two flow paths. And a first electrode and a second electrode.

The second invention is characterized in that the first and second electrodes are made of a fibrous, particulate, mesh or ribbon-shaped conductive member.

According to a third aspect of the present invention, the electrochemical cell main body forms a first flow path at a central portion, and a plurality of second flow paths are formed at a peripheral portion of the diaphragm body in contact with the diaphragm disposed in the first flow path. A road is formed.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front sectional view of a column-type electrochemical cell showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA of a central portion of FIG. 1, FIG. 3 is a left side view of FIG. FIG. 2 is a right side view of FIG. 1.

In FIG. 1, an internal carbon fiber 51 serving as a first electrode is filled in a porous glass tube diaphragm 50 formed of a cylindrical diaphragm in a flow direction of a first electrolytic solution. The fibers 51 are formed by knitting carbon fibers having a diameter of 1.0 μm into approximately 300 filaments and sintering them at a temperature of 2000 ° C. or higher, and have a material that is electrochemically stable. The number of filling is approximately 1000 / cm ² .

As shown in FIG. 2, the porous glass tube diaphragm 50 filled with the carbon fibers 51 is inserted into a through hole 53 serving as a first flow passage formed in the center of the cell body 52. , Then fixed. In the peripheral portion of the through hole 53, a plurality of through holes 55 (4 in FIG.
Book) is drilled. The total cross-sectional area of the through-hole 55 is set to be substantially equal to the internal cross-sectional area of the porous glass tube diaphragm 50.

The cross-sectional shape of the through-hole 55 is most easily manufactured in a circular shape, but it is not necessary to limit the cross-sectional shape to a circular shape, and it may be rectangular or triangular.

Next, means for forming the electrochemical cell main body 52 will be described. The cell body 52 is formed of a rectangular material, and a plurality of through holes 55 are formed in the rectangular material at predetermined positions. Thereafter, a through hole 53 into which the porous glass tube diaphragm 50 is inserted is formed at a predetermined position in the center of the cell body 52.

Here, the inside of the porous glass tube diaphragm 50 is filled with carbon fibers 51, and the porous glass tube diaphragm 50 is inserted into the through holes 53 of the cell body 52, and then the external carbon fibers 54 are passed through the through holes. Fill 55. Thereafter, the protruding carbon fibers 51 and 54 are cut from the axial direction (length direction) of the cell body 52 to complete the electrochemical cell body.

At both ends in the axial direction of the electrochemical cell main body 52, flanges 56 and 57 are provided with O-rings 58 and 59 interposed therebetween, and the first and second electrolytic cells are provided inside and outside the porous glass tube diaphragm 50 with these flanges. Seal so that liquid does not enter. At this time, the O-ring 58 is for sealing the porous glass tube diaphragm 50, and the O-ring 59 is disposed at a position including the through-hole 55 inside, so that the O-rings 58 and 59 are in a liquid-tight state.

The flanges 56 and 57 have inlet holes 60 and 61 and outlet holes 62 for allowing an internal electrolyte (first electrolyte) and an external electrolyte (second electrolyte) to flow in and out, respectively. , 63 are drilled. In particular, with respect to the introduction hole 60 and the discharge hole 63 for the external electrolyte, the holes 64 are circumferentially formed so that the electrolyte flows evenly through the through holes 55 shown in FIG.
65 are drilled.

Next, the inner and outer carbon fibers 51, 5
4 (first and second electrodes), a first electrode rod 66 (internal electrode rod) and a second electrode rod 6
7 (external electrode rod) is inserted. In this embodiment,
As shown in FIG. 2, one internal electrode rod 66 is inserted in the central part and three in the peripheral part, a total of four, and only one central electrode is provided on the flange 57 side. However, it is not necessary to limit to this. It may be provided on the flange 56 side. The insertion hole for the external electrode rod 67 is provided on the flange 57 side.

The electrode retainers 68 and 69 are provided with an electrode rod 66,
The electrode plates 70 and 71 serve as guides for pressing the electrodes against the electrodes 67 and 67 by a spring mechanism.
Then, a path through which current flows through the electrode plate 70 to the internal terminal 75 is formed. Fig.3
It is shown in FIG.

In the above embodiment, the description has been given of the case where the four through holes 55 of the external carbon fiber 54 serving as the second electrode are provided. However, the number of the through holes 55 is not limited to this number. Through hole 5 according to the diameter of rod 67
Needless to say, a sectional area of 5 may be adopted.

Although the description has been made of the case where the inner and outer carbon fibers are formed of thread-like fibers filled along the flow direction of the electrolytic solution, activated carbon or platinum mesh having a short fiber length is used instead. You may do so.

Further, when assembling the electrochemical cell body,
It has been described that the electrode rod is inserted after the fiber is filled into the inside of the porous glass tube diaphragm 50. However, in the case where particulate activated carbon or the like is used instead of the fiber, the electrode rod is disposed first. Later, activated carbon or the like may be pushed. In addition, although only the porous glass tube has been described as the diaphragm, examples of the diaphragm include a cylindrical unfired tube, a cylindrical ion-exchange membrane, and Teflon (registered trademark) having micropores. ) Tubes and the like are also applicable.

The above-described embodiment has the following operation and effect in addition to the above. Since the external electrode rod 67 is inserted into the external carbon fiber 54 to ensure an electrical connection state, the through-hole 55 is provided so that the carbon fiber does not escape laterally when the electrode rod is inserted. , Making assembly easier. Further, the second electrolyte (external electrolyte) is in a conductive state between the through holes 55 filled with the carbon fibers through the gap between the porous glass tube diaphragm 50 and the through holes 53, so that the porous glass The electric resistance between the inside and outside electrodes of the septum 50 is not increased.

Next, as a performance test of the electrochemical cell of the above embodiment, an electrolytic experiment using potassium hexacyanoate (III) and a charge / discharge test of a redox flow battery using vanadium sulfate were performed. The electrochemical cell is
The outer diameter of the porous glass tube diaphragm 50 is 17 mm, the inner diameter is 15 mm, and its length is 120 mm.
300 μm fibers were twisted into a single thread and 1800 fibers were filled in the axial direction. Also, as shown in FIG. 2, the external carbon fibers 54 are arranged at four locations facing each other through holes 55 having a cross-sectional area of 38 mm ^2, and are filled with 500 carbon fibers (the same as the internal carbon fibers) at one location. did. Four first electrode rods 66 and second electrode rods 67 each having a diameter of 3 mm and a length of 120 mm were inserted into the carbon fibers. In addition, Daiflon (trade name) and SUS304 steel were adopted as constituent materials of the electrolytic cell main body 52 and the like.
It is not necessary to limit to this.

For the purpose of examining the electrolytic characteristics of the electrochemical cell constructed as described above, 0.5 mol
/ dm ³ KCl dissolved in pure water was used as a test sample, and 50 mmol / dm ³ potassium hexacyanoferrate (III) K ₃ F
Inject 2 ml of e (CN) ₆ aqueous solution, flow rate 1.0 ml / min, electrolytic potential −
The comparison was made under the condition of 0.1V.

In the experiment, a test electrolyte solution was circulated separately for each of the inner carbon fiber and the outer carbon fiber, and the efficiency of each was measured.
0% of hexacyanoferrate (III) ion is electrolyzed.
It was found to be 100%.

Further, the redo of the electrochemical cell shown in FIG.
The battery shown in the above embodiment as a flow battery cell
For the purpose of examining the characteristics using a electrochemical cell, all vanadium
Of charge and discharge characteristics using aqueous electrolyte solution as battery active material
Was carried out. 2M sulfuric acid as internal electrolyte (first electrolyte)
500 mmol / dm dissolved^ThreeOf vanadium (III) sulfate (V_Two(SO
_Four)_Three2) sulfuric acid as an external electrolyte (second electrolyte)
500mmol / dm dissolved in ^ThreeOf vanadium (IV) sulfate (VO (S
O_Four)_Two) External circulation using aqueous solution at a flow rate of 3 ml / min
Circulated by pump, constant current of 0.5A, 10 cycles
Was subjected to a charge / discharge test. As a result, both
Clone efficiency is over 95%, energy efficiency is over 80%
I wanted something.

If the electrochemical cell having the function shown in FIG. 7 described above is applied to the generation of electrolyzed water, the electrolysis can be performed with high efficiency, and even when the electrolysis is performed at a relatively low potential of the order of 10 mV. There is a feature that the reaction efficiency can be improved. In addition, when applied to a redox flow battery for power storage, a high-performance secondary battery having high energy conversion efficiency and high charge / discharge speed can be obtained. Furthermore, the manufacture and assembly of an electrochemical cell is relatively easy, and therefore, it is a feature that a relatively inexpensive electrochemical cell can be provided.

[0049]

As described above, according to the present invention,
An electrochemical cell main body having first and second electrolytes formed therein with respective introduction holes and discharge holes; and a first and second electrolytes formed in the cell main body and introduced from the respective introduction holes. First and second flow paths leading to the respective discharge holes, and both flow paths are formed so as not to mix with both electrolytes flowing through the first and second flow paths. A diaphragm made of a porous member disposed in the first flow passage so as to cause a reaction, and inserted into the first and second flow passages partitioned by the diaphragm, and a And the first and second electrodes to which a voltage is applied so as to make the potential distribution uniform in order to cause an electrochemical reaction in the electrode. With high energy efficiency and fast reaction speed Together perform the discharge, it can be advantageously produced, also assembled to provide easy cell.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a column-type electrochemical cell showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line AA of a central portion of FIG.

FIG. 3 is a left side view of FIG. 1;

FIG. 4 is a right side view of FIG. 1;

FIG. 5 is a front sectional view showing a conventional electrolytic cell.

FIG. 6 is a schematic configuration diagram of a redox flow battery.

FIG. 7 is a schematic configuration diagram of a flat plate type electrolytic cell.

[Explanation of symbols]

 Reference Signs List 50: porous glass tube diaphragm 51: internal carbon fiber 52: electrochemical cell body 53: through hole 54: external carbon fiber 55: through hole 56, 57: flange 58, 59: O-ring 60, 61: introduction hole 62, 63 ... discharge hole 66 ... first electrode rod (internal electrode rod) 67 ... second electrode rod (external electrode rod) 68, 69 ... electrode holder 70, 71 ... electrode plate 72 ... connection terminal

Claims (3)

[Claims] 1. An electrochemical cell main body having first and second electrolytic solution inlet holes and discharge holes formed therein, and first and second electrolytic cells formed in the cell main body and introduced through the respective inlet holes. A first and a second flow path for guiding the two electrolytes to the respective discharge holes; and forming the two flow paths so as not to mix the two electrolytes flowing through the first and the second flow paths. And a diaphragm made of a porous member disposed in the first flow path so as to cause an electrochemical reaction, and inserted into the first and second flow paths partitioned by the diaphragm, In order to cause an electrochemical reaction between both channels,
And a first electrode and a second electrode to which a voltage is applied so that a potential distribution is uniform. 2. The column-type electrochemical cell according to claim 1, wherein the first and second electrodes are formed of a fibrous, particulate, mesh, or ribbon-shaped conductive member. 3. The electrochemical cell body according to claim 1, wherein a first part is provided at a central part.
2. The column-type electric device according to claim 1, wherein a flow path is formed, and a plurality of second flow paths are formed around the diaphragm body in contact with the diaphragm body provided in the first flow path. Chemical cell.